Active thermal insulation system including evacuated structures and a vacuum sustaining unit

ABSTRACT

A thermal insulation system includes an evacuated structure including an internal space in which a vacuum is sustained by a vacuum pump operating when it is determined that a pressure within the internal space has risen to a predetermined level. In one embodiment, such a system is used within a dome structure extending over and around a heat receiving structure within a solar heating system.

RELATED APPLICATIONS

Not Applicable

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to thermal insulation systems, more particularly to such systems including evacuated structures, and yet more particularly to the use of such systems to allow heat retention within solar heat collectors.

double glazed vacuum structures, and, more particularly, to such structures having a means for providing and maintaining a vacuum between spaced-apart glass sheets for thermally insulating solar heat collectors.

2. Summary of the Background Information

A solar heat collector typically includes a heat receiving structure through which a fluid, such as water, is circulated to be heated by solar radiation. The heat receiving structure comprises elements such as piping, tubing, a reservoir tank, and a thermally conductive structure to absorb heat from radiant energy and to transmit the heat to the fluid. Preferably, a transparent cover is placed over the heat receiving structure, allowing the passage of radiant energy, so that the vessel is heated by sunlight, while minimizing the conduction of heat, allowing the heat receiving structure to rise to a relatively high temperature without substantial heat losses to the atmosphere around the solar heat collector. The effectiveness of the thermal insulation in preventing heat loss to the atmosphere has a significant effect on the overall efficiency of the solar heat collector, particularly when the solar heat collector is operated in a cold climate.

One method that has been applied to provide thermal insulation while allowing the transmission of radiant energy is the use of a pair of glass plates that are spaced apart to form an intervening air space. A single plate of glass has an insulation value of R1, with this value being increased to R2 when a second plate is installed to provide a separate air space. Evacuating the air within the space between the glass plates can provide substantially higher insulation values of R30 to R50, at the cost of a need to provide air tight seals around the edges of the glass plates and of a need to provide a structure that can withstand a pressure of about 15 psi acting on each of the plates. However, the use of structures including evacuated spaces for thermal insulation has been the brittleness and relatively low strength of the glass materials generally used and by a lack of reliability of such structures in large thermally insulating systems because small leaks result in a loss of vacuum.

The patent literature includes a number of descriptions of structures for reducing the transfer of heat through the use of spaced-apart glass plates on opposite sides of an evacuated space. For example, U.S. Pat. No. 2,216,332 describes a window including a pair of spaced-apart glass plates and a pipe extending within the wall from the space between the glass plates. The pipe extends to a valve that can be opened to withdraw air form the space between the plates or to return air to this space. A supporting structure, composed of slotted, interlocking vertical and horizontal spacers dividing the space between the plates into a number of smaller rectangular spaces, extends between the plates to help resist the atmospheric pressure acting on the plates when air is removed from this space.

U.S. Pat. No. 3,990,201 describes a An evacuated dual pane window structure is provided for reducing heat loss through the window structure. The window structure comprises a pair of closely spaced panes of glass having a spacing of less than 0.25 inch with a spacer means positioned between and uniformly spaced in the area between the panes, and sealing means such as an 0-ring positioned around the perimeter and between the panes of glass. A vacuum=pump may be provided for evacuating the area between the panes of glass for reducing thermal losses through the window structure. Reflective coatings may ;′ be provided on the inside surfaces of the glass. A plurality of windows of the above structure may be connected by manifold piping to a single vacuum pump, which is actuated by a thermostat when a preset temperature differential exists between the outside and the inside of the building where the windows are used.

U.S. Pat. No. 4,184,480 describes a conventional flat plate solar heat collector provided with a contoured vacuum insulation window supported solely about its peripheral edge portions. The window is a composite formed from a pair of minimum thickness complementarily contoured glass sheets, which with the exception of their peripheral portions which are sealed together, are spaced apart from one another so as to provide an evacuated chamber therebetween and thus insulate one sheet from the other. The window formed by the nested or complementary contoured glass sheets is contoured in both its longitudinal and lateral directions, such that in its longitudinal direction the window is composed of a plurality of sinusoidal corrugations whereas in its lateral direction the peaks of such corrugations are contoured in the form of paraboloids so as to provide maximum uniform tensile strength to the window such that it may withstand the forces generated thereon by the atmosphere. However, the size of the insulated glass member is limited by the forces, principally caused by the air pressure acting on the two glass sections, and possibly additionally by manufacturing and transportation difficulties associated with handling and forming large pieces of glass. What is needed is a method for a way to provide a thermally insulating cover over a larger and taller solar heat collector.

Other patents describe methods for sealing the interface between glass plates and structural framing members and for providing channels for the evacuation of air between the glass plates to form thermally insulating structures. For example, U.S. Pat. No. 6,383,580 describes a vacuum insulating glass (IG) unit and method-of making the same. An edge-mounted pump-out structure is provided, including a pre-positionable insert capable of receiving a pump-out tube therein. Following formation of the edge-mounted pump-out structure and its positioning on the unit, an edge seal is formed for hermetically sealing off the low pressure space located between the substrates.

U.S. Pat. No. 6,506,272 describes a A vacuum insulating glass (IG) unit. In certain embodiments, the internal cavity is evacuated (i.e., pumped out) via a pump-out aperture. A cover with one or more sealing element(s) may be provided over the pump-out aperture so that during the pump-out process air flows out of the internal cavity and through space(s) between adjacent sealing elements or sealing element portions. Following evacuation or pumping out, the sealing element(s) is/are heated and the sealing member may be pressed downwardly toward the substrate. This causes the heat-softened sealing element(s) to expand horizontally and merge with one another so as to form a hermetic seal around the pump-out aperture and between the sealing member and the substrate.

U.S. Pat. No. 5,902,652 describes a method for providing pillars to space apart thermally insulating glass panels that are spaced apart, a method for providing an improved edge seal around the glass panels, and a method for providing an improved pump-out tube for use during construction of the panels.

SUMMARY OF THE INVENTION

Various difficulties and shortcomings of prior-art thermally insulating systems including evacuated spaces are overcome through the use of the present invention. A dome-shaped central space within a thermally insulating system is provided for holding the heat-receiving portion of a solar heating system. The mechanical weakness of glass panels extending adjacent evacuated spaces is overcome by curving the panels and, optionally, additionally by providing a panel with an impact-resistant film coating and by composing a panel of a ceramic glass material. In applications where transparency is not needed, a strong and resilient material, such as a metal, is used in place of the glass. The reliable, long-term use of large thermally insulating systems is achieved through the use of vacuum sustaining units to make the systems tolerable of small leaks.

In accordance with a first aspect of the invention, a thermally insulating system including a thermally insulating structure and a vacuum sustaining unit is provided, with the thermally insulating structure including an internal space. The vacuum sustaining unit includes a first input tube connected to the internal space, a pressure sensor sensing a pressure within the internal space, and a vacuum pump evacuating air from the internal space in response to a signal from the pressure sensor indicating that a pressure within the internal space has risen above a predetermined level.

In accordance with a first embodiment of the invention, the thermally insulating structure includes a floor structure and a dome-shaped structure, extending upward from the from the floor structure. The dome-shaped structure includes an internal surface forming a central space extending from the internal surface to the floor structure, and an external surface. Preferably, the heat-receiving portion of solar heating system is disposed within the central space. The internal space extends within the dome-shaped structure, separate from the central space and between the internal and external surfaces. The dome-shaped structure transmits solar radiation from outside the dome-shaped structure to the central space within the dome-shaped structure.

Preferably, the floor structure includes a flat inner plate, a flat outer plate, a frame, and a second input tube. The flat inner plate and the flat outer plate are each composed of a strong and resistant material. The frame holds the flat inner and outer plates in a spaced-apart relationship, forming an inner space extending within the frame and between the flat inner and outer plates. The second input tube connects the inner space within the floor structure with the vacuum sustaining unit.

In accordance with a first version of the first embodiment, the dome-shaped structure comprises an inner transparent dome, and outer transparent dome, a gasket, and at least one bracket. The inner transparent dome includes the inner surface, a first lower surface, and a lower flange extending outwardly around the first lower surface. The outer transparent dome includes the external surface, a second lower surface, and an upper flange extending outwardly around the second lower surface.

In accordance with a second version of the first embodiment, the dome-shaped structure includes a dome-shaped framework having a plurality of frame openings. An inner transparent curved sheet and an outer transparent curved sheet are held in a spaced-apart relationship within each of the frame openings, with the spaces between the transparent curved sheets being connected to one another to form the internal space. The dome-shaped framework may additionally include a removable frame section, an access door that can be opened to provide access to the central space, or an opening extending around a lens concentrating solar radiation within the central space.

In accordance with a second embodiment of the invention, the thermally insulating structure comprises a plurality of thermally insulating panels. Each of the thermally insulating panels includes flat inner and outer panels and a frame. The flat inner and outer panels are each composed of a strong and resilient material, The frame holds the flat inner and outer panels in a spaced-apart relationship, forming an inner space extending within the frame and between the inner and outer plates. The inner space within each of the thermally insulating panels is connected to the vacuum sustaining unit, by a common evacuation tube, or by openings extending through adjacent portions of the frames of adjacent thermally insulating panels.

In accordance with a first version of the second embodiment, the thermally insulating panels are aligned along a surface, such as a wall, floor, or ceiling, within a building, or are disposed within an element of a building, such as a wall ceiling, or floor, between elongated members within the element.

In accordance with a second version of the second embodiment, the thermally insulating panels form a box structure, extending around a central space, and a first door structure. The box structure includes an access opening. The door structure is movable between a closed position, extending within the access opening, and an open position. An insulating panel within the door structure is connected to the vacuum sustaining unit by a path including a flexible hose. The box structure may extend within a refrigerator, a container, or a railroad car.

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 is a plan view of a thermal isolation system built in accordance with a first version of a first embodiment of the invention;

FIG. 2 is a cross-sectional elevation of the thermal isolation system of FIG. 1, taken as indication by section lines 2-2 therein;

FIG. 3 is a fragmentary cross-sectional elevation of the thermal insulation system of FIG. 1, taken as indicated by section lines 3-3 therein.

FIG. 4 is a schematic view of a vacuum sustaining unit built in accordance with the invention to sustain a vacuum within an inner space of a thermal isolation system, such as the system of FIG. 1;

FIG. 5 is a perspective view of a thermal insulation system built in accordance with a second version of the first embodiment of the invention, extending over and around a solar heat collector;

FIG. 6 is a fragmentary plan view of a frame within the solar heat collector of FIG. 5;

FIG. 7 is a fragmentary elevation of a dome-shaped helical structure within the solar heat collector of FIG. 5, shown in a straightened condition;

FIG. 8 is a fragmentary cross-sectional plan view of a dome-shaped structure within the thermal insulation system of FIG. 5;

FIG. 9 is a perspective view of the dome-shaped structure of FIG. 8;

FIG. 10 is a transverse cross-sectional view of a frame member within the dome-shaped structure of FIG. 8;

FIG. 11 is a first transverse cross-sectional view of a frame member at a removable frame section within the dome-shaped structure of FIG. 8;

FIG. 12 is a second transverse cross-sectional view of the frame member of FIG. 11;

FIG. 13 is a fragmentary cross-sectional plan view of a dome-shaped structure including an access door, for alternative use within the thermal insulation system of FIG. 5;

FIG. 14 is a first transverse cross-sectional view of a frame member pivotally mounting the access door of FIG. 13;

FIG. 15 is a transverse cross-sectional view of a frame member latching the access door of FIG. 13;

FIG. 16 is a second transverse cross-sectional view of the frame member of FIG. 14;

FIG. 17 is a third transverse cross-sectional view of the frame member of FIG. 14;

FIG. 18 is a perspective view of a thermal insulation system including a lens concentrating solar radiation within a solar heat collector disposed therein;

FIG. 19 is a perspective view of the thermal insulation system of FIG. 5 extending over an opening concentrating solar radiation within a solar heat collector disposed therein;

FIG. 20 is a perspective view of a thermal insulation system including a Fresnel lens concentrating solar radiation on the solar heat collector of FIG. 19;

FIG. 21 is a fragmentary cross-sectional elevation of the Fresnel lens of FIG. 21;

FIG. 22 is a plan view of portions of a floor structure within the thermal insulation system of FIG. 5, showing the portions in an exploded relationship;

FIG. 23 is a fragmentary perspective view of a frame within the thermal insulation system of FIG. 5;

FIG. 24 is a fragmentary perspective view of a first alternative version of the frame of FIG. 5;

FIG. 25 is a fragmentary perspective view of a second alternative version of the frame of FIG. 5;

FIG. 26 is a plan view of an elongated version of the dome-shaped structure within the thermal insulation system of FIG. 5;

FIG. 27 is a cross-sectional end elevation of a thermally insulating panel used within a second embodiment of the invention;

FIG. 28 is a fragmentary front elevation of a thermal insulation system including a number of the insulating panels of FIG. 27 extending along a wall;

FIG. 29 is a fragmentary front elevation of a thermal insulation system including a number of the insulating panels of FIG. 27 extending within a wall;

FIG. 30 is a cross-sectional plan view of a refrigerator including versions of the insulating panel of FIG. 27;

FIG. 31 is a first cross-sectional end elevation of the refrigerator of claim 30, taken as indicated by section lines 31-31 therein;

FIG. 32 is a second cross-sectional end elevation of the refrigerator of claim 30, taken as indicated by section lines 31-31 therein;

FIG. 33 is a cross-sectional plan view of a container including versions of the insulating panel of FIG. 27;

FIG. 34 is a first fragmentary cross-sectional elevation of the container of FIG. 33 showing a first method for connecting the insulating panels therein;

FIG. 35 is a second fragmentary cross-sectional elevation of the container of FIG. 34 showing a second method for connecting the insulating panels therein; and

FIG. 36 is a cross-sectional plan view of a railroad car including versions of the insulating panel of FIG. 27.

DETAILED DESCRIPTION OF THE INVENTION

A solar heat collector typically includes a heat receiving structure through which a fluid, such as water, is circulated to be heated by solar radiation. The heat receiving structure comprises elements such as piping, tubing, a reservoir tank, and a thermally conductive structure to absorb heat from radiant energy and to transmit the heat to the fluid. Preferably, a transparent cover is placed over the heat receiving structure, allowing the passage of radiant energy, so that the vessel is heated by sunlight, while minimizing the conduction of heat, allowing the heat receiving structure to rise to a relatively high temperature without substantial heat losses to the atmosphere around the solar heat collector. The effectiveness of the thermal insulation in preventing heat loss to the atmosphere has a significant effect on the overall efficiency of the solar heat collector, particularly when the solar heat collector is operated in a cold climate or if it is desired to operate the solar heat collector at a relatively high temperature needed for the production of mechanical power to drive an electrical generator. For example, a copending U.S. patent application Ser. No. 12/009,092, filed Jan. 16, 2008, the disclosure of which is incorporated herein by reference, describes a solar heating system including dome-shaped apparatus that is heated by solar radiation. Other descriptions of solar heating systems including dome-shaped heat receiving structures are found in the disclosures of U.S. Pat. Nos. 4,057,048, 4,136,670, 4,305,383, and 5,427,628, each of which is incorporated herein by reference.

FIGS. 1-3 show a thermal insulation system 110 including a dome-shaped structure 112, built for enclosing a dome shaped heat receiving structure within a solar heat collector within a central space 114. FIG. 1 is a plan view of the thermal insulation system 110, with FIG. 2 being a cross-sectional elevation thereof, taken as shown by section lines 2-2 in FIG. 1, and with FIG. 3 being a fragmentary cross-sectional elevation thereof, taken as shown by section lines 3-3 in FIG. 1.

The dome-shaped structure 112 includes an outer transparent dome 116 and an inner transparent dome 118, each including a hemispherical portion 120 and a flange 122. A number of alignment brackets 124 fasten the dome-shaped structure 112 to a floor structure 126 by means of bolts 128, with a resilient gasket 130, disposed between the flanges 122 of the transparent domes 116, 118, sealing an internal space 132 therebetween, and allowing the evacuation of the internal space 132 by a vacuum sustaining unit 133. An input tube 134 from the vacuum sustaining unit 133 extends through the resilient gasket to draw air from the space 132 between the transparent domes 116, 118. The flanges 122 may be formed as integral portions of the transparent domes 116, and 118, as shown in FIG. 2, or as separate structures rigidly attached to the hemispherical portions 120 as shown in FIG. 3.

The thermal insulation system 110 is additionally prepared for the installation of solar heat collecting apparatus (not shown) which preferably has overall dome-shaped structure, within the dome-shaped central space 114 by providing a fluid inlet tube 136 and a fluid outlet tube 138, each of which extends from an area 140 outside the dome-shaped structure 112 into the dome-shaped inner space 114, for the circulation of a fluid through the solar heat collecting apparatus.

Preferably, the floor structure 126 is formed as a thermally insulating vacuum panel structure including a flat inner plate 142, a flat outer plate 144, and a frame 146, which are attached and sealed to one another so that an internal space 148 is formed, with the internal space 148 being evacuated by the vacuum sustaining unit 133 through an evacuation tube 150. Preferably, the flat plates 142, 144 are composed of a tough, resilient material, such as a metal or a reinforced plastic, since transparency is not needed. The floor structure 126 may also include a number of spacers 152 extending between the panels 142, 144 to resist the tendency of the pressure acting on these panels 142, 144 to push these panels 142, 144 together. The spacers 152 may, for example, be cylindrical or elongated.

It is noted that the shape of the hemispherical portions 120 of each of the transparent domes 116, 118 is considered ideal for resisting internal and external pressure. Evidence of this is seen in the design of tanks for storing gas at relatively high internal pressures, which are generally spherical or cylindrical with hemispherical ends, and in the design of deep diving equipment, including diving helmets and submersible vehicles, which generally include spherically shaped surface for resisting high external pressures. Nevertheless, if additional structure is needed to maintain the space 132 between the transparent domes 116, 118, spacers (not shown) may be attached to extend between the transparent domes 116, 118.

FIG. 4 is a schematic view of vacuum sustaining unit 133 built in accordance with the invention for use in a thermally insulating system including evacuated spaces, such as the thermally insulating system 110 described above in reference to FIGS. 1-3. The vacuum sustaining unit 133 includes an input tube 172 attached, for example, to the evacuation tube 134 of the thermal insulation system 110. The vacuum sustaining unit 133 additionally includes a vacuum pump 174, which pulls air from the input tube 172 to be expelled through an opening 176 in the a housing 178. Preferably, a check valve 180 allows the outward movement of air, in the direction of arrow 182 while preventing a reverse flow of air, opposite the direction of arrow 182. A pressure sensor 184 may also be included, turning on the vacuum pump 174 when the pressure within the input tube 172 is above a predetermined level and turning the vacuum pump 174 off when the pressure within the input tube 172 is low enough. The pressure sensor 184 may also provide an input signal to operate an indicator light 186, turning on the indicator light 186 when the vacuum pump 174 is being driven. For example, a constantly running vacuum pump 174 would mean that the vacuum sustaining unit 133 could not keep up with an air leak, indicating a need for repairs.

While, in the example of FIG. 4, the pressure sensor is shown within the housing 178 of the vacuum sustaining unit 133 to measure a pressure within the interior space 132 of the dome-shaped structure 112 by its effect on the pressure within the input tube 172, which is connected to the interior space 132, it is understood that the pressure sensor 184 may alternatively be placed within the interior space 132 to measure this pressure directly. It is additionally understood that additional indicator lights 144 may be connected to the vacuum sustaining unit 133 through wired or wireless connections to provide similar indications at various locations.

Thus, through operation of the vacuum sustaining unit 133, the dome shaped structure 112 and the floor structure 126 become evacuated structures, with air being evacuated from the internal space 132 of the dome-shaped structure 112 and the internal space 148 of the floor structure 126. As the term is used herein, the evacuation of air does not mean that a perfect vacuum is achieved or approximated, but rather that a pressure low enough to substantially reduce the transfer of heat is achieved.

FIG. 5 is a perspective view of a thermal insulation system 250 including a dome-shaped structure 252 built in accordance with a second version of the first embodiment of the invention to extend around and over a dome-shaped solar heat collector 254 built as described in detail in U.S. patent application Ser. No. 12/009,092, the disclosure of which has been incorporated herein by reference. A front portion of the dome-shaped structure 252 has been cut away to show the structure of the solar heat collector 254, which includes a frame 256, having a plurality of frame elements 258, and a plurality of transverse elements 260. Each of the frame elements 258 includes a pair of rigid tubular elements 262, extending parallel to one another. The lower ends 264 of rigid tubular elements 262 within adjacent frame elements 258 are connected to one another by peripheral tubular elements 266 within the frame 256.

FIG. 6 is a fragmentary plan view of the frame 256, showing a central portion thereof, including an upper plate 268 an a lower plate 270, fastened together by screws 272. The upper ends 274 of the rigid tubular elements 262 within each of the frame elements 258 are connected to one another, forming a single fluid path 276 extending through the frame 256 from an inlet end 278 to an outlet end 280. As shown in FIG. 7, each of the transverse elements 260 includes a pair of flexible tubular elements 282. For example, the rigid tubular elements 262, 266 are formed from sections of metal pipes, while the flexible tubular elements 282 are formed from a hose 283.

FIG. 7 is a fragmentary elevation of a single dome shaped helical structure 284, shown in a straightened condition. The single dome shaped helical structure 284 is formed from a single section of hose 283 to include the plurality of the transverse elements 260, with the dome shaped helical structure 284 extending between a first end 286 and a second end 288. At the first end 286 of the dome shaped helical structure 284, a first fluid path 290 formed within a first hose segment 292, is connected to a fluid source (not shown), and a second fluid path 294, formed within a second hose segment 296 is connected to a fluid receiver (not shown). At the second end 288 of the dome shaped helical structure 284, the hose segments 292, 296 are connected to one another. Thus, each of the transverse elements 260 includes a portion of the first hose segment 292 and a portion of the second hose segment 294, with fluid flowing in opposite directions within the hose segments 292, 296. As shown in FIG. 5, the first end 286 of the dome shaped helical structure 260 extends outward so that connections to the hose segments 292, 294 can be made. For example, a fluid is driven into the first hose segment 292 at the first end.

FIG. 8 is a fragmentary cross-sectional plan view of the dome-shaped structure 252, extending around the dome shaped solar heat, collector 254. In particular, sections of the frame elements 258 within the frame 256 are shown, along with an adjacent pair of transverse elements 260, each of which extends around a circular pattern 300 formed by the frame elements 258. The transverse elements 260 are interwoven with the frame elements 258 so that each transverse element 260 extends across the frame elements 258 alternately inside, in the direction of arrow 302, or outside, in the direction of arrow 304 adjacent frame elements 258. In addition, transverse elements 260 adjacent one another cross each frame element 258 on opposite sides of the frame element 258, i.e. inside the frame element 258 or outside the frame element 258. In a preferred embodiment of the invention, adjacent transverse elements 260 are connected to one another to form a single dome shaped helical structure 284 extending in a helical pattern around and along the frame elements 258, with all of the transverse elements 260 being sections of the single dome shaped helical structure 284. For these conditions to be met, the solar heat conducting dome 254 must have an odd number of frame elements 258, such as the seven frame elements 258 shown in the figures.

FIG. 9 is a perspective view of the dome-shaped structure 252 extending around and over the dome-shaped solar heat collector 254. The dome-shaped structure 252 includes a frame 320 having frame members 322 including horizontal frame members 324 and vertically extending frame members 326, intersecting with one another to form a plurality of frame openings 327. The dome-shaped structure 252 additionally includes base members 328 attached to the lowermost horizontal frame members 324 and to a floor structure 330 (shown in FIG. 5). The inlet and outlet ends 278, 280 of the frame 256, and the first end 286 of the dome-shaped helical structure 284 extend outwardly through holes 332 in the base members 328. As shown in the cross-sectional frame views of FIGS. 5 and 8, each of the frame members 322 includes slots 334 holding adjacently extending outer transparent curved sheets 336 and inner transparent curved sheets 338. Optionally, upper panels 340 may be opaque, since the plate 268 within the frame 256, disposed below the panels 340, is opaque. Preferably, the dome-shaped structure 252 includes a vertically extending frame member 326 outwardly adjacent each of the frame elements 258, allowing the dome-shaped structure 252 to be placed closer to the solar heat collector 254, since the transverse elements 260 are held inward, extending between adjacent frame elements 258.

FIG. 10 is a transverse cross-sectional view of a frame member 322. Spaces 342 between outer transparent curved sheets 336 and inner transparent curved sheets 338 are connected by a channel 340 extending through the frame member 322, allowing air within the spaces 342 to be evacuated simultaneously. Sealing material 344 is provided to prevent or at least minimize a flow of air into the spaces 342. The input tube 172 from a vacuum sustaining unit 133, operating as described above in reference to FIG. 4, is connected to one of the spaces 342 to sustain a vacuum within all of the spaces 342 by the movement of air through channels 340 between the spaces 342.

For example, the transparent curved sheets 336, 338 are composed of glass or of a transparent thermoplastic material. Shattering may be prevented by attaching an impact resistant film to one or more of the surfaces 345 of the transparent curved sheets 336, 338. Furthermore, significant strengthening may be achieved by composing either or both of the transparent curved sheets 336, 338 of a transparent ceramic material.

FIGS. 11 and 12 are transverse cross-sectional views of a frame member 345 showing optional provisions made therein for removing a removable frame section 346, including an outer transparent curved sheet 336 and an inner transparent curved sheet 338. Such provisions, which may be made to provide for the removal of one or more removable frame sections 346 for performing maintenance on the heat collector 254, include splitting the frame member 322 into an outer frame member section 348 and an inner frame member section 350, which are held together by a number of screws 352. A gasket 354 is provided around the removable frame section 346 at the interface between the section members 348, 350. Removing the frame member section 346 by loosening the screws 352, provides access through the dome-shaped structure 252.

FIG. 13 is a fragmentary cross-sectional plan view of a lower portion 370 of a dome-shaped structure 372, extending around a lower portion 374 of a solar heat collector 376 built in accordance with another embodiment of a solar heat collector described in detail in U.S. patent application Ser. No. 12/009,092. The solar heat collector 376 includes an upper portion built as shown in FIG. 16 and the lower portion 374 built as shown in FIG. 17 to include a space 378 between adjacent frame elements 380, through which a person can enter a region 384 within the solar heat collector 376 to enjoy the heat in the manner of a sauna. Similarly, the dome-shaped structure 372 includes an upper portion built as shown in FIG. 16 and the lower portion 370 built as shown in FIG. 17 to include an access door 386 pivotally mounted by hinges 388 to be opened in the direction of arrow 390.

The mounting and latching of the door 386 will now be discussed with reference being made to FIGS. 14 and 15. FIG. 14 is a transverse cross-sectional view of a frame member 392 at which the access door 386 is pivoted, taken through one of the hinges 388 joining the frame member 392 and the access door 386. The cross-sectional view is taken perpendicular to an axis of rotation formed by the pins 389. The access door 386 and the frame member 392 are curved outward to present surfaces 393 between a pair of the hinges Each of the hinges 388 is mounted on spacers 394 so the axis formed by the pins is outwardly disposed from the surfaces 393.

FIG. 15 is a transverse cross-sectional view of a frame member 395 at which the access door 386 is latched. A knob 396, rotatably mounted in the access door 386, is attached to a pawl 400 engaging a latching tab 402 within the frame member 395. When the knob 396 is rotated ninety degrees, the pawl 400 is moved out of alignment with the latching tab 402, allowing the access door 386 to be pivoted open in the direction of arrow 390. A resilient pad 404 may be included to increase a level of force acting between the pawl 400 and the latching tab 402. A handle 405, rotating with the knob 396 is provided for opening the access door 386 from inside the access door 386. While a simple latching mechanism has been described above, it is understood that a conventional latching mechanism of a form well known to those skilled in the art of designing and installing doors, including, for example, a locking knob or latch, could be readily used in this application.

FIGS. 16 and 17 are additional transverse cross-sectional views of the frame member 392, showing an upper end 406 and a lower end 407, respectively, of a tube assembly 408 connecting a space 410 between transparent curved sheets 412 within the door 386 with a space 414 between transparent curved sheets 416 adjacent to the door 386. The tube assembly 408 includes a formed upper rigid tube 418 connected to the space 414, a formed lower rigid tube 420, connected to the space 416 and a flexible tube 422 extending between the rigid tubes 418, 420. Preferably, the flexible tube 422 is axially aligned with the pivot pin 389 of the hinge 388, so that movement of the door 386 is accommodated by torsional deflection within the flexible tube 422, allowing the space 410 within the door 386 to remain evacuated as the door 386 is opened and closed.

FIG. 18 is a fragmentary perspective view of a dome-shaped structure 440 extending around a solar heat collecting dome 442 built in accordance with another embodiment of a solar heat collector described in detail in U.S. patent application Ser. No. 12/009,092. Both the dome-shaped structure 440 and the solar heat collecting dome 442 are shown with front portions thereof removed to reveal internal details. The solar heat collecting dome 442 includes an opening 444 allowing the direct transmission of radiant solar energy into an internal space 446 within the frame 448 and transverse elements 450 of the dome 442. For example, in the dome 442, the upper plate 268 and the lower plate 270, discussed above in reference to FIG. 6, are replaced with a ring 452 including the opening 444, in which a lens 454 is held. The ring 452 also includes transparent curved sheet attachment features 455 for the attachment of adjacent transparent curved sheets 464 within the dome-shaped structure 440.

The lens 454 concentrates solar radiant energy on a dish-shaped absorber 456 located, for example at the focal plane of the lens, above a floor structure 458. The dish-shaped absorber 456 absorbs energy that heats the air within the internal space 446, and additionally reflects a portion of the solar radiant energy to heat the frame 448 and transverse elements 450. An electrically-driven fan 452 is preferably additionally provided to circulate air within the internal space 446. Preferably, the dish-shaped absorber 456 is spaced away from the floor structure 458, so that the fan 452 can circulate air both above and under the disk-shaped absorber 456. The dish-shaped absorber 456 may be covered with thermally absorbing and reradiating materials, such as rusty steel plates. The internal space 446 may additionally include a reservoir 460 holding fluid stored at the elevated temperature of the space 446 for later use. The reservoir 460 may be connected to a fluid path within the frame 448, within the transverse elements 450 or elsewhere. Other aspects of the dome-shaped structure 440 and the solar heat collecting dome 442 are as described above in reference to FIGS. 5 and 9.

FIG. 19 is a fragmentary perspective view of an alternative dome-shaped structure 470 extending around and over a solar heat collecting dome 472 including an alternative provision for allowing the entry of radiant solar energy into an internal space 474 within a frame 476 and transverse elements 478. The upper plate 268 and the lower plate 270, discussed above in reference to FIG. 13, are replaced with a ring 480 including an opening 482 extending from above the ring 480 into the space 474. Optionally, a lens may be held within the opening 482 to concentrate radiation on elements within the space 474. The alternate dome-shaped structure is similar to the dome-shaped structure 252 described above in reference to FIG. 12, except that transparent curved sheets 476 to allow solar radiation to shine into the opening 482, instead of being optional. For example, the alternate dome-shaped structure 470 and the solar heat collecting dome 472 are otherwise identical to the solar heat collecting dome 254 and the dome-shaped structure 252, respectively, described above in reference to FIG. 5.

FIG. 20 is a perspective view of a dome-shaped structure 500 including brackets 502 supporting elongated members 504 holding a lens assembly 506 in place over the dome-shaped structure 500. For example, the solar heat collecting dome 472, described above in reference to FIG. 19, is disposed within the dome-shaped structure 500, with solar radiation being concentrated on the solar heat collecting dome 472 by the lens assembly 506.

FIG. 21 is a fragmentary cross-sectional elevation of the lens assembly 506, showing an annular frame 508 holding a Fresnel lens 510 in place between a pair of protective transparent sheets 512. While a convex lens can alternatively be used this say, the use of a Fresnel lens provides significant size and weight savings.

FIG. 22 is a plan view of floor portions 520 of the floor structure 330, discussed above in reference to FIG. 5, in an exploded relationship with one another. For example, the floor structure 330 has been divided into two floor portions 520 to simplify its transportation. Each of the floor portions 520 includes a flat inner plate 522, shown as partially cut away to reveal details within the floor portion 520, and a flat outer plate 524. The flat plates 522, 524 are composed of a strong and resilient material, such as a metal or a reinforced plastic. A frame 526 holds the flat plates 522, 524 in a spaced-apart relationship with one another, forming an internal space 527 within each of the floor portions 520. Preferably, a number of spacers 528 additionally hold the flat plates 522, 524 apart when the internal spaces 527 are evacuated. The floor portions 520 are connected to one another with conventional hardware (not shown), such as screws and brackets, with a connecting tube 530, extending within a gasket 532, connecting the inner spaces 526. A second input tube 534 connects one of the internal spaces 527 with the input tube 172 of the vacuum sustaining unit 133, discussed above in reference to FIG. 4.

Thus, through operation of the vacuum sustaining unit 133, the dome shaped structure 250 (shown in FIG. 5) and the floor structure 330 become evacuated structures, with air being evacuated from internal spaces 342 (shown in FIG. 10) of the dome-shaped structure 250 and from internal spaces 127 of the floor structure 126. As the term is used herein, the evacuation of air does not mean that a perfect vacuum is achieved or approximated, but rather that a pressure low enough to substantially reduce the transfer of heat is achieved.

FIG. 23 is a fragmentary perspective view of the frame 254, described above in reference to FIG. 9, holding outer transparent curved sheet 336 and an inner transparent curved sheet 338 (shown in FIG. 10) within a frame opening 327. The frame 254 and the transparent curved sheets 336, 338 are curved inward, in the direction of arrow 540, and upward, in the direction of arrow 548, but are straight in the direction of arrow 550, extending around the frame 254.

FIGS. 24 and 25 are fragmentary perspective views of alternative versions of the frame 254. In a first alternative frame version 560, shown in FIG. 24, the frame 560 and the transparent curved sheets 336, 338 are straight in the upward direction of arrow 562, while being curved in the direction of arrow 550, extending around the frame 560. In the second alternative frame version 564, the frame 564 and the transparent curved sheets 336, 338 are curved inward, in the direction of arrow 540 and upward, in the direction of arrow 548, and additionally in the direction of arrow 550, extending around the frame 564.

Curving the transparent sheets 336, 338 as shown in FIGS. 23-25 increases the strength and stiffness of these sheets 336, 338 in resisting the atmospheric pressure applied to these sheets 336, 338 when the space 342 between these sheets 336, 338 is evacuated. In this way, a significant advantage is gained over prior art systems in which flat transparent sheets are used. The curvature of the sheets 336, 338 allows these sheets 336, 338 to be composed of a brittle material, such as glass, or of a flexible material, such as a transparent thermoplastic material, without requiring the use of a multitude of spacers, which in themselves add to thermal conductivity. Furthermore, curving the vertical frame members 326, as shown in FIGS. 23 and 25, increases the strength and stiffness of these frame members 326 in regard to gravitational forces acting on these members 326. It is noted that various curved dome structures have been associated since ancient times with an ability to span relatively long distances within a structure without a need for intervening pillars. The vertical frame members 326 may be curved along a the path of a circular arc or along a path, such as a parabolic or catenary path traditionally associated with providing an ability to resist gravitational loading.

FIG. 26 is a plan view of an elongated version 570 of the dome-shaped structure 252, described above in reference to FIGS. 5 and 9. Preferably, each of the vertical frame members 572 within the elongated dome 570 is curved in the manner

FIG. 27 is a cross-sectional end elevation of a thermally insulating panel 610 built for use within a thermally insulating structure built in accordance with a second embodiment of the invention, which to include a plurality of such insulating panels 610 attached to a vacuum sustaining unit 133, as described above in reference to FIG. 4.

The insulating panel 610 includes a pair of side panels 612 held in a spaced-apart condition within a frame 614. An evacuation tube 616 extends through the frame to provide for the evacuation of air from the interior space 618 between the side panels 612, and seals 620 prevent, or at least minimize, the return of air into the interior space 618 following evacuation. In the example of FIG. 27, the side panels 612 are composed of an opaque material, such as a metal, plastic, or composite material including wood chips. Spacers 622 may be attached to extend between the side panels 612, preventing deflection and possible breakage of the side panels 612 due to atmospheric pressure applied by the air around the insulating panel 610.

The thermal insulation panel 610 of FIG. 27 is readily useful in architectural applications for separating areas to be held at different temperatures. For example, at least a portion of the interior space within a structure may be thermally isolated from the temperature outside the building, substantially reducing the cost of heating and air conditioning within the building, or a single room may be thermally isolated from other areas in the building. With the active vacuum method of the invention it is practical to provide efficient thermal insulation along large areas using a number of panels 610 within a building, because small leaks, which may occur due to the settling of the building or due to the aging of materials, are taken care of by automatic operation of one or more vacuum sustaining units 133, described above in reference to FIG. 4.

FIG. 28 is a fragmentary front elevation of a thermal insulation system 700 covering a wall 702 and including a number of thermal insulation panels 610, each of which is attached to the inner surface 704 of the wall 702. The evacuation tube 616 of each of the thermal insulation panels 610 is connected to a vacuum sustaining unit 133 through a manifold tube 706. Each of the thermal insulation panels 610 may be covered with a decorative cover 708. The piping, including the manifold tube 706 may be surrounded by conventional insulation 710 to reduce thermal transfer below the panels 610 and is covered by a trim strip 712. The thermal insulation system 700 may be installed after the wall 702 is finished, and may even be applied to an existing building after its construction.

FIG. 29 is a fragmentary front elevation of a thermal insulation system 720 built into a wall 722, and including a number of thermal insulation panels 610. An exhaust tube 616 from each of the insulation panels 610, is attached to a vacuum sustaining unit 133 through a manifold tube 724. The wall 722 includes a number of elongated support members 726. Conventional insulation 730 is placed in various locations not occupied by the panels 610. The wall is additionally covered by a wall board material 732, which is generally shown as cut away to reveal internal details. A front panel 734 of the vacuum sustaining unit 133 extends through the wall board material 730.

While FIGS. 28 and 29 show insulating panels 610 placed against or within walls, it is understood that such panels 610 can readily be placed against or within other elements within a building, such as floors and ceilings, according to the invention.

Versions of the thermal insulation panel 610 may be used within appliances to form internal spaces that can be cooled or heated to a desired temperature with very little transfer of heat to or from the ambient air. For example FIGS. 30-32 show a thermal insulation system 740 within a refrigerator 742, with FIG. 30 being a cross-sectional plan view of the refrigerator 742, and with FIGS. 31 and 32 each being a cross-sectional side elevation thereof. FIG. 31 is taken as indicated by section lines 31-31 in FIG. 30 to show elements within a thermal insulation box structure 744 and in a door insulation panel 746. FIG. 32 is taken as indicated by section lines 32-32 in FIG. 30 to show the pivotal mounting of a door 748 holding the door insulation panel 746 and the connection of an evacuated space 750 within the door insulation panel 746 and an evacuated space 752 within the box structure 744.

Referring first to FIGS. 30 and 31, the thermal insulation system 740 includes a thermal insulation box structure 744 having a pair of thermally insulating side panels 754, a thermally insulating rear panel 756, a thermally insulating top panel 758, and a thermally insulating lower panel 760. An opening 760 at a front side 762 of the box structure 744 is covered by the door 748 when closed, with sealing being provided by a flexible gasket 764 extending around the opening 760. The box structure 744 includes a frame 766 having corner frame members 768 holding panel plates 770 extending in directions perpendicular to one another and front frame members 772 extending around the opening 760, holding panel plates 770 extending rearward. A vacuum is maintained within the evacuated spaces 752 within the box structure 742 through the operation of a vacuum sustaining unit 133, configured as described above in reference to FIG. 4. The input tube 172 (shown in FIG. 4) of the vacuum sustaining unit 133 is connected to the box structure 744 by a connecting tube 774 and to the various evacuated areas 752 within the box structure 744 by openings 776 extending through the corner frame members 768. The refrigerator 742 includes conventional elements, such as an external cover 778, an internal cover 780 and a door cover 782.

Referring to FIG. 32, the door 748 is pivotally attached to the main portion 784 of the refrigerator 742 by means of an upper pin 786 extending downward from an upper bracket 788 and a hollow lower pin 790 extending upward from a lower bracket 792. The space 750 within the door insulation panel 746 is connected to a space 752 within one of the thermally insulating side panels 744 by a flexible tube 794 extending through the hollow lower pin 790, so that the opening and closing motion of the door 748 is accommodated by twisting an elongated portion 796 of the flexible tube 794, with the elongated portion 796 preferably being coaxially aligned with the pins 786, 790.

FIG. 33 is a cross-sectional plan view of a container 800 including an evacuated structure 802 including a box structure 804 having an access opening 804 at a rear end 806 and a pair of door structures 808. The container 800 may be of the type that is loaded on a ship, a railroad car, or on a truck trailer. Alternately, the container 800 may form a permanent part of a truck trailer. Each of the door structures 808 is disposed within a door 810 of the container 800, with the door 810 being pivotally mounted by a hinge 812 to moved between the closed position in which it is shown and the open position indicated by dashed lines 814. The panels 610 are generally constructed as described above in reference to FIG. 27. Preferably, the panels 610 extend along each side 820 of the container 800, along the front end 822 thereof, along the floor 824 thereof, and along the ceiling (not shown) thereof, being inwardly disposed, and attached to, structural elements of the container 800, such as ribs 826. All of the internal spaces 618 (shown in FIG. 27) of the panels 610 are connected to one or more vacuum sustaining units 133, discussed above in reference to FIG. 4, which may be located inside the container 800, as shown, or outside the container 800.

FIG. 34 is a first fragmentary cross-sectional elevation of the container 800, showing a first method for connecting the internal spaces 618 to a vacuum sustaining unit 113. Each of the panels 610 includes an evacuation tube 830, which is connected to a manifold tube 832 extending along a corner of the box structure 804. All of the manifold tubes 822 are connected to the vacuum sustaining unit 133, with the connections being made, for example, by welding or by screw thread attachment.

FIG. 35 is a second fragmentary cross-sectional elevation of the container 800, showing a second method for connecting the internal spaces 618 to a vacuum sustaining unit 133. The internal spaces 618 within adjacent panels 610 are connected through a tube 834 extending through a gasket 836 At least one of the panels 610 is directly connected to a vacuum sustaining unit 133. Internal spaces 618 within the door structures 808 are connected to internal spaces 618 within the box structure 804 by flexible tubes extending in alignment with the hinges 812 as described above in reference to FIGS. 30-32.

The vacuum sustaining unit 133 may be operated through the use of a rechargeable battery that is plugged into the electrical system of a truck carrying the container. Furthermore, the container 800 may additionally include a refrigeration system (not shown) sharing a power source with the vacuum sustaining unit 133. Alternatively, the unit 133 may not be provided with the container 800, with an external connection to a manifold tube 832 being instead provided for periodic use of an external version of the vacuum sustaining unit 133.

FIG. 36 is a cross-sectional plan view of a railroad car 850, which is, for example, an insulated boxcar or refrigerator car, in which an insulating structure 852 is installed. This insulating structure 852 is similar to the insulating structure 802 within the container 800, described above in reference to FIG. 33, except that different provisions are made for the access doors 854, each of which includes a door structure 856 having thermally insulating panels 610. Each access door 854 is movably mounted using standard railroad car hardware providing a plug-door arrangement, in which the access door 854 is moved outward before being slid along a track 858 for opening, and closed by being moved inward after sliding along the track 858. In the figure, the access door 854 in a first side 860 of the railroad car 850 is shown in a closed position, while the access door 854 on a second side 862 of the railroad car 854 is shown in an open position, so that access is provided through an opening 864

The insulating panels 610 within each of the door structures 856 are connected with the insulating panels 610 within a box structure 860 by means of a flexible tube 864 resting within a tray 866. Preferably, the tray 864 is installed near the roof of the railroad car 850, with the tubes 862 being attached near the top of the doors 854.

While the invention has been shown in its preferred embodiments and versions with some degree of particularity, it is understood that this description has only been given by way of example, and that many changes can be made without departing from the spirit and scope of the invention, as defined by the appended claims. 

1. A thermally insulating system comprising: a thermally insulating structure including an internal space; a vacuum sustaining unit including a first input tube connected to the internal space, a pressure sensor sensing a pressure within the internal space; and a vacuum pump evacuating air from the internal space in response to a signal from the pressure sensor indicating that a pressure within the internal space has risen above a predetermined level.
 2. The thermally insulating system of claim 1, wherein the thermally insulating structure includes a floor structure and a dome-shaped structure, extending upward from the floor structure, the dome-shaped structure includes an internal surface forming a central space extending from the internal surface to the floor structure, and an external surface, the internal space extends within the dome-shaped structure, separate from the central space and between the internal and external surfaces, and the dome-shaped structure transmits solar radiation from outside the dome-shaped structure to the central space within the dome-shaped structure.
 3. The thermally insulating system of claim 2, wherein the dome-shaped structure comprises: an inner transparent dome including the inner surface, a first lower surface and a lower flange extending outwardly around the first lower surface; an outer transparent dome including the external surface, a second lower surface, upwardly disposed from the first lower surface, and an upper flange extending outwardly around the second lower surface; a gasket extending between the lower flange and the upper flange to enclose a space extending between the inner and outer transparent domes to form the internal space; and at least one bracket holding the inner and outer transparent domes in a spaced-apart relationship.
 4. The thermally insulating system of claim 3, wherein: the lower flange is formed as a separate piece within the inner transparent dome, and the upper flange is formed as a separate piece within the outer transparent dome.
 5. The thermally insulating system of claim 2, wherein the dome-shaped structure comprises; a dome-shaped framework including a plurality of frame openings; an inner transparent curved sheet and an outer transparent curved sheet held within each frame opening within the plurality of frame openings, wherein the inner and outer transparent curved sheets are held in a spaced-apart relationship to form a portion of the internal space; and a plurality of openings connecting the portions of the internal space in adjacent frame openings to form the internal space.
 6. The thermally insulating system of claim 5, wherein the dome-shaped framework additionally comprises a removable frame section, removable from outside the dome-shaped structure, the removable frame section extends around one of the frame openings, and the removable frame section holds the inner and outer transparent curved sheets within the frame opening in the removable frame section.
 7. The thermally insulating system of claim 5, wherein the dome-shaped framework additionally comprises a door section mounted to be moved between an open position and a closed position, and a flexible tube extending between the door and an adjacent surface of the dome-shaped framework; access from outside the dome-shaped structure to the central space within the dome-shaped structure is provided with the door section in the open position and prevented with the door section in the closed position the door section extends around one of the frame openings, the door section holds the inner and outer transparent curved sheets within the frame opening in the door section, and the flexible hose connects the portion of the internal space between the inner and outer transparent curved sheets within the frame opening in the door section with the portion of the internal space within an adjacent frame opening.
 8. The thermally insulating system of claim 5, wherein the dome-shaped framework additionally includes an opening extending around a lens concentrating solar radiation within the central space.
 9. The thermally insulating system of claim 5, additionally comprising a Fresnel lens held above the dome-shaped structure to focus solar radiation on the dome shaped structure.
 10. The thermally insulating system of claim 5, wherein the dome-shaped structure and the dome-shaped framework are elongated.
 11. The thermally insulating structure of claim 5, wherein the inner and outer transparent curved sheets are curved around a circumference of the dome-shaped structure.
 12. The thermally insulating structure of claim 5, wherein the inner and outer transparent curved sheets are curved to extend inward and upward.
 13. The thermally insulating structure of claim 5, wherein a plurality of the transparent curved sheets are composed of a transparent ceramic.
 14. The thermally insulating system of claim 2, wherein the floor structure includes: a flat inner plate composed of a strong and resilient material; a flat outer plate composed of a strong and resilient material; a frame holding the flat inner and outer plates in a spaced-apart relationship and forming an inner space extending within the frame and between the flat inner and outer plates; and a second input tube connecting the inner space within the floor structure with the vacuum sustaining unit.
 15. The thermally insulating system of claim 2, wherein the internal surface of the dome-shaped structure extends around and over a heat receiving portion of a solar heating system.
 16. The thermally insulating system of claim 1, wherein the thermally insulating structure comprises a plurality of thermally insulating panels, each of the thermally insulating panels includes a flat inner plate composed of a strong and resilient material, a flat outer plate composed of a strong and resilient material, and a frame holding the flat inner and outer plates in a spaced-apart relationship and forming an inner space extending within the frame and between the flat inner and outer plates, and the interior space within each of the thermally insulating panels is connected to the vacuum sustaining unit.
 17. The thermally insulating system of claim 15, wherein the interior space within each of the thermally insulating panels is connected to the vacuum sustaining unit by a common evacuation tube.
 18. The thermally insulating system of claim 15, wherein interior spaces within adjacent thermally insulating panels are connected by openings extending through adjacent portions of the frames within the adjacent thermally insulating panels.
 19. The thermally insulating system of claim 15, wherein the thermally insulating panels are aligned along an interior surface within a building.
 20. The thermally insulating system of claim 15, wherein the thermally insulating panels are disposed between elongated members within a structural element within a building.
 21. The thermally insulating system of claim 15, wherein the thermally insulating panels form a box structure, extending around a central space, and a first door structure, the box structure includes a first access opening. the door structure is movable between a closed position, extending within the first access opening, and an open position, access into the central space is provided with the door structure in the open position and prevented with the door structure in the closed position, and an insulating panel within the first door structure is connected to the vacuum sustaining unit by a path including a first flexible hose.
 22. The thermally insulating system of claim 20, wherein the box structure is disposed within a refrigerator, and the first door structure is disposed within a pivotally mounted door of the refrigerator.
 22. The thermally insulating system of claim 20, wherein the box structure is disposed within a container, the first access opening is disposed at an end of the container, the thermally insulating panels additionally form a second door structure, movable between a closed position, extending within the first access opening, and an open position, the first door structure is disposed within a first pivotally mounted door of the container, the second door structure is disposed within a second pivotally mounted door of the container, access into the central space is provided with each door structure in the open position and prevented with each door structure in the closed position. and an insulating panel within the second door structure is connected to the vacuum sustaining unit by a path including a second flexible hose
 23. The thermally insulating system of claim 20, wherein the box structure is disposed within a railroad car, the first access opening is disposed within a first side of the box structure, the box structure additionally includes a second access opening, disposed within a second side of the box structure, the thermally insulating panels additionally form a second door structure, movable between a closed position, extending within the second access opening, and an open position, the first door structure is disposed within a first slidably mounted door of the railroad car, the second door structure is disposed within a second slidably mounted door of the railroad car, access into the central space is provided with either door structure in the open position and prevented with each door structure in the closed position. and an insulating panel within the second door structure is connected to the vacuum sustaining unit by a path including a second flexible hose.
 24. Solar heating apparatus comprising: a heat receiving structure through which a fluid flows to be heated by solar radiation, and a thermally insulating structure, including a floor structure and a dome-shaped structure, extending upward from the floor structure, wherein the dome-shaped structure includes an internal surface forming a central space holding the heat-receiving structure and extending from the internal surface to the floor structure, an external surface, and an evacuated internal space extending within the dome-shaped structure, separate from the central space and between the internal and external surfaces, and wherein the dome-shaped structure transmits solar radiation from outside the dome-shaped structure to the central space within the dome-shaped structure.
 25. The solar heating apparatus of claim 24, wherein the floor structure includes: a flat inner plate composed of a strong and resilient material; a flat outer plate composed of a strong and resilient material; a frame holding the flat inner and outer plates in a spaced-apart relationship and forming an evacuated inner space extending within the frame and between the flat inner and outer plates;
 26. A thermal insulating unit, disposed with a container, comprising: a plurality of thermal insulating panels, wherein spaces within each of the thermal insulating panels are connected to one another and to an exterma; connection for evacuation of air through the external connection. 